During the past year Dr. Ohwaki has determined the effects of pH, carbon dioxide concentration, and medium composition on the recovery of bacteria from dental plaque obtained from patients suffering from Sjogren's syndrome. Three strains of yeast have been identified and a large number of bacterial isolates have been obtained for further identification. Future work will include estimates of the viable mass in plaque using extractable adenosine triphosphate. Because patients suffering from Sjogren's syndrome have xerostomia and suffer from severe caries problem, it will be of interest to determine the fraction of the total mass which is viable in these plaque samples. We hope that the caries problem associated with this disease will serve as a model for the investigation of a pathogenic plaque and allow us to apply a variety of analytic methods being developed in this laboratory to the investigation of the nature of such plaque.